Keyboard encoder



April 1966 A. SCHONFELD ETAL 3,248,052

KEYBOARD ENCODER 3 Sheets-Sheet 1 Filed June 25, 1964 FIG. 1

FIG. 2

IN VE N TORS ARNOLD SCHONFELD MARVIN JACOBY TREVOR D. READER ATTORNEYS FIG. 6

April 1966 A. SCHONFELD ETAL 3,248,052

KEYBOARD ENCODER Filed June 25, 1964 5 Sheets-Sheet 3 FIG.

6.9 TOLL United States Patent 3,248,052 KEYBDARD ENCODER Arnold Schonfeld, Levittown, Marvin Jacoby, Fort Washington, and Trevor D. Reader, King of Prussia, Pa., assignors to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Filed June 25, 1964, Ser. No. 377,933 11 Claims. (Cl. 235-445) The present invention relates to keyboard input devices of a type suitable for use with digital data processing and control systems. More particularly, the present invention provides a novel keyboard construction including means responsive to actuation of a key for producing a plurality of fluid output signals each of which represents a bit of a character expressed in a binary code.

An object of this invention is to provide a keyboard for producing coded combinations of fluid output signals, said keyboard having no moving mechanical parts other than the keys.

An object of this invention is to provide a novel keyboard comprising a plurality of stacked plates, at least some of said plates having channels formed in one surface thereof, said plates having holes extending therethrough for the purpose of connecting together the channels in different plates, and key means for selectively admitting fluid to predetermined ones of said channels.

An object of this invention is to provide a data encoder for producing output signals representing bits of a character expressed in a second code in response to input signals representing characters expressed in a first code.

The encoder comprises a source of fluid, a plurality of fluid operated logical. OR circuits, one for each bit of a character expressed in the second code, a plurality of channel means connecting the source to the inputs of the OR circuits, and a plurality of key means, one for each character of said first code, each key means including means for normally blocking one of the channel means and means defining an aperture positionable in alignment with its corresponding channel means when the key means is actuated.

An object of the invention is to provide a plurality of OR circuit means responsive to fluid input signals for producing fluid output signals on a plurality of output channels, there being one output channel for each bit of a character expressed in a second code, a manually actuated fluid switch for each character of a first code, fluid conveying means'connecting the outputs of the fluid switches to the inputs of the OR circuit means in accordance with the second code, and means for supplying fluid to the switches, each of the switches passing the fluid supply thereto to its output when actuated.

A feature of the invention is the provision of a keyboard comprising four stacked plates. The three bottom plates have a plurality of channels formedin the upper surface thereof. The two intermediate plates of the stack have holes extending therethrough for the purpose of connecting together in a predetermined pattern the channels in the three lower plates of the stack. A key is provided for each possible character to be encoded.

All four plates are provided with additional holes for receiving the keystem associated with each key. The keystem holes for the two lower plates are made somewhat larger than the size of the keystem and a stop means is mounted on the lower end of each keystem to limit upward movement of the key. Each key and its associated stem is constantly urged upward by a compression spring. Each keystem has a hole therein which comes into alignment with the channel in the second plate when the key is depressed. This permits fluid to flow through predetermined ones of the channels in the three lower plates in order to produce a coded combination of fluid output signals corresponding to the key depressed.

Other objects of the invention and its mode of operation will become apparent upon consideration of the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 shows the arrangement of the keys on the keyboard;

FIGURE 2 is a side view, partly in section, showing some of the details of the keyboard construction;

FIGURE 3 shows a typical key assembly; and,

FIGURES 4, 5, 6, and 7 show the details of the upper surfaces of the top, second, third, and bottom plates, respectively.

The basic principles of the invention are described herein as applied to a keyboard encoder for encoding the decimal digits 0 through 9 in the excess-3 binary code. .However, as will become evident from the following description, these basic principles may be employed for encoding alphabetic as well as numeric characters and fluid output signals may be produced in codes where each character is represented by a unique combination of any desired number of bits.

Referring now to FIGURES 1 through 3, keyboard 10 comprises four substantially flat plates 12, 14, 16, and 18. As subsequently explained, the bottom surface of each of these plates is substantially flat and the top surface of each of the plates 14, 16, and 18 has a configuration of channels formed therein. The top of the keyboard is to the left when viewing FIGURE 2. The plates are held together in a fluid-tight relationship to prevent leakage of fluid from the keyboard between surfaces of adjoining plates. This may be accomplished by means of an adhesive, screws or other suitable fastening means (not shown).

Fluid is continuously applied to the keyboard through an input tube 20 which connects with a channel 22 formed in the upper surface of plate 14. As shown in FIGURE 5 channel 22 has a plurality of branches 22 through 22 connected therewith so that fluid supplied to the channel from tube 20 may flow along any one of ten diflerent paths. Each of these branch paths terminates at a hole 24 which extends through plate 14 from its top to its bottom surface. Each of these holes is normally blocked by a keystem so that fluid cannot flow through the branch channel 22 unless the corresponding key has been depressed.

FIGURE 2 shows the details of the O-key assembly. The 1 through 9 key assemblies are similar to the O-key assembly except for the size of the key pad or top 26 which is preferably made larger for the zero key because it is customarily actuated by the operators thumb.

I The zero key assembly includes the key top or pad 26 mounted on top of a keystem 28 and a stop element 30 secured to the bottom of the keystem by means of a screw or other suitable fastening means 32.

A recess 34 is formed in the upper surface of top plate 12 and a hole 36 extends through plate 12 from its bottom surface to the recess. The holes 24 and 36 are aligned when the keyboard plates are stacked. These holes are made slightly larger than the keystem 28 so that the keystem may slide freely within the holes. However, clearance between the keystem and the walls of the holes should be kept to a minimum in order to avoid excessive leakage of the fluid out of the keyboard around the keystem.

A compression spring 38 surrounds the keystem and is compressed between the key top 26 and the bottom of the recess 34 thus tending to move the key assembly to the left. This movement is limited by the stop element 30 which is larger than the hole 24 and thus rests against the bottom of plate 14. Preferably, the length of the keystem is chosen such that when the stop element is against the bottom surface of plate 14 the key top 26 does not clear the top surface of plate 12. Because of the square shape of the key tops this prevents rotation of the key assembly.

Plates 16 and 18 have holes 4ti and 42 formed therein. These holes are axially aligned with each other and with the holes 24 and 36. Holes 4tl and 42 are made slightly larger than the stop element 30 to permit free movement of the stop element in the holes as the key is depressed.

A hole 44 extends through the keystem. As shown in FIGURE 2 this hole normally rests within the plane of plate 12. However, the key acts as a fluid switch of the on-ofi' type and upon depression of the key the hole 44 moves into alignment with channel 22 thus permitting fluid to fiow from channel 22 into channel 46. This fluid then flows through the channels in plates 14, 16, and 18 in a manner subsequently described to produce fluid output signals representing decimal as expressed in the binary excess-3 code. These output signals appear in tubes 2 2 2 and 2 and may be fed into pressure actuated switches to provide an electrical output or they may be channeled directly to some other mechanism in order to perform some work function.

FIGURE 4 is a top view of plate 12. This plate has 10 recesses 34 through 34 formed in its upper surface with a hole 36 through 36 centrally located in each recess and extending through the plate to its bottom surface. As explained above, the recesses 34- receive the key tops 26 while the key-stems 28 extend through the holes 36. Plate 12 has no channels formed therein for the purpose of conveying fluid signals.

FIGURE is a top view of plate 14. As previously explained, the upper surface of this plate has the channel 22 formed therein which is connected by means of tube 20 to a source which continuously supplies fluid to the channel. Channel 22 branches into ten separate channels 22 through 22 each of which terminates at its downstream extent at one of the holes 24 through 24. These holes are normally blocked by the keystems. When a particular keystem is depressed the hole in the keystem provides a connecting passage so that fluid may fiow from one end of the channels 22 into a corresponding channel 46. Each channel 46 has a hole 43 associated therewith. The holes extend downwardly through the plate from the bottom of the channels so that fluid flowing through a particular one of the channels 46 may flow downwardly through the corresponding hole 48 and be distributed to the channels in plates 16 and 18.

j Plate 14 also has a channel 50 formed in its upper surface. At one end of the channel a hole 52 extends downwardly through the plate to its bottom surface and at the other end is a hole 54 which also extends downwardly through the plate. As subsequently explained in greater detail, channel 50 and holes'52 and 54 merely serve as a connecting link between two channels in the upper surface of plate 16.

FIGURE 6 is a top view of plate 16. This plate has ten holes 40 through 40 extending through the plate from its top to its bottom surface. There is one of these holes axially aligned with each keystem with each hole being of sufficient diameter to permit free movement of a stop element 30 therethrough when a key is depressed. Formed in the upper surface of the plate are a plurality of channels 58 through 73. Extending through the plate to its bottom surface are a plurality of holes 74 through 81 and 121. The exact location and function of these channels and holes will become obvious from the functional description given subsequently. However, it may be noted at this point that the channels 63, 69, 70, 71 are the output channels. The combination of fluid pressure signals appearing in these output channels provides an indication of the key being depressed at any given time. This indication being given in the binary excess-3 code for the particular embodiment shown.

The configuration of channels in the upper surface of plate 16 is such that two fluid operated logical OR circuits 82 and 84 are formed. OR circuit 82 receives input signals from channels 59 through 63 and provides output signals through channel 58. The sides of channels 59 through 63 are tapered and these channels terminate at their downstream extent at a plurality of orifices radially disposed about a receiving orifice 86. The walls of channel 58 are tapered at the upstream extent of the channel to form orifice 86. The arrangement is such that a fluid signal moving through one of the channels 59 through 63- exits from the orifice at the downstream extent of the channel and moves through the orifice 86 into the output channel 58.

The channel 73 extends to the outer edges of plate 16 and communicates with the surrounding environment. The purpose of channel 73 is to prevent a build-up of pressure in the 0R circuit which might feed back into the system and appear erroneously as a data signal. For example, assume that a signal is applied to the OR circuit through channel 62 and is directed towards orifice 86. If a pressure build-up is permitted in the region or orifice 86 this pressure might travel back through channel 61 and appear as an input signal to OR circuit 84. Channel 73 prevents this pressure buildup.

OR circuit 84 is constructed in the same manner as OR circuit 82. Channels 61 and 64 through 67 are tapered at their downstream extent and terminate at orifices aimed at, and radially disposed about, the receiving orifice 88. Output channel '70 is tapered at its upstream extent to form the orifice 88 so that the fluid output signal is produced in channel if an input signal is applied to the OR circuit through any one of the channels 61 and 64 through 67. Channel 72 communicates with the-surrounding environment and provides pressure relief for OR circuit 84.

FIGURE 7 is a top view of plate 18. Extending through this plate from its top to its bottom surface are ten holes 42 through 42 These holes are the same size as holes 40 in plate 16 and are positioned such that when the keyboard is assembled each hole 42 is in alignment with a corresponding hole 40.

Formed within the top surface of plate 18 are a plurality of fluid channels 91 through 1.00. These channels are aranged to form two logical OR circuits 102 and 104 similar to the OR circuits previously described. OR circuit 102 receives input signals from channels 91 through and these signals pass through aperture 106 to output channel 99 of the OR circuit. OR circuit 104 receives input signals from channels 93 and 95 through 98 and these signals pass through an orifice 108 to the output channel of this OR circuit.

The juncture of each OR circuit is vented to the atmosphere through a channel 110 in order to prevent any pressure build-up at the junctures from feeding back into the system through the input channels to the OR circuits. Since channel 110 passes through the junction points for the two OR circuits it is possible that a pressure build-up at the junction of one OR circuit might be transferred to the other OR circuit over the channel 110. In order to prevent this two additional channels 112 and 114 are provided. Each of these channels 5 vents to the surrounding atmosphere at one end and c011 nects with channel 110 at the other end, the connections with channel 110 being disposed between the junction points of the two OR circuits.

Table I shows the combination of output signals which should be developed in output channels 68, 69, 70, and 71 (FIGURE 6) when each key is depressed. A binary 1 represents the presence of a fluid signal which may be manifested by the presence of fluid flow or a first pressure and a binary represents the absence of a fluid signal which may be manifested by the absence of fluid flow or a second pressure. The paths for producing these signals will now be traced in detail.

Table I Key Channel Channel Channel Channel 0-key.-When the 0-key is depressed output signals should be produced on channels 69 and 71 of FIGURE 6. These signals are produced as follows. In FIGURE 5, fluid flows from input tube 20 through channel 22, channel 22, the hole in the O-keystem, and channel 46 to the hole 48. The fluid then flows downwardly through hole 48 and the hole 90 (FIGURE 6) to the channel 93 shown in FIGURE 7. The fluid enters channel 93 in the region designated 120 and flows through the channel in both directions from this region. A part of the fluid kows to the right and into OR circuit 104 from whence it passes into channel 100. At the end of channel 100 this fluid flows upwardly through the hole 81 in plate 16 (FIGURE 6) and then into output channel 71.

Returning to FIGURE 7, a portion of the fluid entering channel 93 moves to the left and enters OR circuit 102 from whence it flows into channel 99. At the end of channel 99 this fluid moves upwardly through the hole 80 in plate 16 (FIGURE 6) and then into output channel 69.

J-key.--Ta1ble I shows that when the l-key is depressed fluid output signals should appear only in output channel 68. The path for fluid' flow is as follows. In FIG- URE 5, from tube 20 through channels 22 and 22 the hole in the lkeystem, channel 46 to hole 48 The fluid flows downwardly through hole 48 to channel 59 shown in FIGURE 6. It then flows through OR circuit 82 into channel 58. At the end of channel 58 the fluid moves upwardly through the hole 52 in plate 14 (FIG- URE 5). From hole 52 the fluid flows through channel 50 to hole 54 and then moves downwardly through plate 14 to the output channel 68 (FIGURE 6).

2-key.-When the 2-key is depressed output signals should be produced on channels 68 and 71. Fluid flows from tube 20 through channels 22 and 22 through the hole in keystem 2, channel 46 to hole 48 The fluid flows downwardly through hole48 to the channel 63 and hole 74 shown in FIGURE 6. The fluid then branches into two paths. The first path of flow is through channel 63, OR circuit 82 and channel 58 (FIGURE 6) then upwardly through hole 52 (FIGURE 5) through channel 50, downwardly through hole 54 and into output channel 68. The other path of flow is downwardly through hole 74 into the channel 97 shown in FIGURE 7. From channel 97 this fluid flows through OR circuit 104 into channel 100'. At'the end of channel 100 the 6 fluid moves upwardly through the hole 81 (FIGURE 6) and into output channel 71.

3-key.-Upon depression of the 3-key fluid flows from tube 20 through channel 22, 22 the hole in keystem 3, channel 46 to hole 48 The fluid moves downward-1y through hole 48 and enters channel 62 (FIGURE 6) in the region 122. At this point the fluid divides into two paths. The first path is through OR circuit 82 to channel 58, up through hole 52 (FIGURE 5) through channel 50, and down through hole 54 to output channel 68. The second path is downwardly through hole 75 into channel 94 (FIGURE 7) through OR circuit 102 into channel 99, up through hole (FIGURE 6) to output channel 69.

4-.key.-Upon depression of the 4-key fluid flows from tube 20 through channels 22 and 2-2 through the hole in the 4-keystem, channel 46 to the hole 48 Fluid moves downwardly through hole 48 and enters channel 60 (FIGURE 6) in the region of hole 76. At this point the fluid divides into three distinct paths. The first path is downwardly through hole 76 into channel 92 (FIGURE 7) through OR circuit 102, channel 99, upwardly through hole 80 (FIGURE 6) to output channel 69.

The second path is through channel 60, OR circuit 82, channel 58, upwardly through hole 52 (FIGURE 5) through channel 50, downwardly through hole 54 to output channel 68.

The third path is through channel 60, downwardly through hole 121 to channel 96 (FIGURE 7) through OR circuit 104, channel 100, upwardly through hole 81 (FIGURE 6) to output channel 71.

5-key.0n depression of the S-key fluid flows from tube 20 through channels 22 and 22 the hole in keystem 5, channel 46 and downwardly through 48 to channel 66 (FIGURE 6) thence through OR circuit 84 to output channel 70.

6-key.--Upon depression of the 6-key fluid flows fro tube 20 through channels 22 and 22 the hole in keystem 6, channel 46 downwardly through hole 48 to channel 67 (FIGURE 6). At this point the fluid divides into two paths. The first path is through channel 67, and OR circuit 84 to output channel 70'.

The second path is downwardly through hole 77 to channel 98 (FIGURE 7) and then through OR circuit '104, channel 100 upwardly through hole 81 (FIGURE 6) to output channel 71.

7-key.--Upon depression of the 7-key fluid flows from tube 20 through channels 22 and 22", the hole in keystem 7, channel 46", downwardly through hole 48 to channel 65 (FIGURE 6). At this point the fluid divides into two paths. The first path is through channel 65, and OR circuit 84 to output channel 70.

The second path is downwardly through hole 78 to channel 91 (FIGURE 7) through OR circuit 102, channel 99, upwardly through hole 80 (FIGURE 6) to output channel 69.

8-key.-When the 8-key is depressed fluid flows from tube 20 through channels 22 and 22 through the hole in keystem 8, channel 46 donwardly through hole 48 to channel 64. At this point the flow divides into two paths. The first path is through channel 64, and OR circuit 84 to output channel 70.

The second path is downwardly through hole 79 to channel 95 (FIGURE 7). The fluid enters channel 95 in the region 124 and again divides into two paths. The first path is through OR circuit 102, channel 99, upwardly through hole 80 (FIGURE 6) output channel 69. The second path is through channel 95, OR circuit 104, channel 100, upwardly through hole 81 (FIGURE 6) to output channel 71.

9-key.-When the 9-key is depressed fluid flows from tube 20 through channels 22 and 22 the hole in the 9- keystem, channel 46 downwardly through hole 48 to 7 the channel 61 in FIGURE 6. The fluid enters channel 61 in the region 126 and divides into two paths. The

first path is through OR circuit 84 to output channel 70. The second path is through OR circuit 82, channel 58, upwardly through hole 52 (FIGURE through channel 50, downwardly through hole 54- to output channel 68.

From the foregoing description it is obvious that the present invention provides a keyboard construction requiring no moving parts other than the keys. Thus, the device is not subject to wear and requires little maintenance. The simple design is readily adapted to mass production techniques thus enabling the keyboard mech anism to be produced at very low cost. The plates of the keyboard may be made of plastic, ceramic, metallic or other materials and the channels may be formed therein by means of a molding, etching, engraving or other suitable process.

It will be understood that in actual practice the channels formed in the surfaces of plates 14, 16, and 13 may be much smaller than depicted herein. In a typical embodiment, the signal channels may be approximately -.08 in. deep and .08 in. wide. In such an embodiment the keys may be spaced apart by a distance of of an inch and the keystem holes 36 may be approximately 34 inch in diameter. These dimensions are given by way of illustration only and are not intended as limiting the invention. Obvious modifications of the embodiment herein disclosed may be made without departing from the spirit and scope of the invention as defined in the appended claims. For example, an embodiment may "be constructed having no movable keys. In such an embodiment the fluid switching might be accomplished by blocking orifices in keystems in the manner disclosed in Wadey Patent No. 3,034,628. Although the present invention has been described as producing output signals having numerical significance it should be understood that the signals may also be used for control purposes. Thus, the principles of the invention disclosed herein may be incorporated into keyboards suitable for controlling various functions. In alternative embodiments it may be desirable to use either more or less than four plates and/ or more or less than ten keys, this number being shown herein only for purposes of illustrating the principles of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A data encoder for producing output signals representing bits of a character expressed in a second code in response to input signals representing characters expressed in a first code, said encoder comprising: a source of fluid; a plurality of fluid operated logical OR circuits, one for each bit of a character expressed in said second code, each of said OR circuits having a plurality of inputs and an output; a plurality of channel means connecting said source to the inputs of said O'R circuits; and a plurality of key means one for each character of said first code, each key means including means for normally blocking one of said channel means and means defining an aperture positionable in alignment with its channel means when the corresponding key means is actuated.

2. A data encoder for producing output signals representing bits of a character expressed in a second code in response to inputs representing characters of a first code, said encoder comprising: means defining a first plurality of paths for fluid flow; a movable element disposed at the downstream extent of each of said first paths for normally blocking the corresponding path; means defining a second plurality of paths for fluid flow each terminating at its upstream extent at one of said movable elements, said paths converging at their downstream extent in combinations dependent upon said second code; and means defining a plurality of output paths for fluid flow one path for each bit of said second code, each of said movable elements having an aperture therein which interconnects selected ones of said first and said second plurality of paths when said movable element is moved.

3. A data encoder as claimed in claim 2 wherein said means defining said first and said second plurality of paths and said output paths comprises a plurality of stacked plates, each of said plates except the top plate having a configuration of channels formed in one surface thereof and each of said plates except the top and bottom plates having a plurality of holes extending therethrough to permit fluid fiow between said channels.

4. A data encoder as claimed in claim 3 wherein said movable elements are keystems, each of said plates having a hole therein for receiving each of said keystems.

5. A data encoder as claimed in claim 4 and further comprising: a key mounted on each keystem, resilient -means urging said key and keystem in a first direction and retaining means on each keystem for limiting the movement of the keystem in said first direction.

6. A data encoder as claimed in claim 5 wherein each retaining means comprises means larger than a keystem attached to the bottom of a keystem, the holes in at least the bottom plate being smaller than said retaining means whereby said retaining means abuts the bottom of one of said intermediate plates to limit movement in said first direction.

7. A data encoder as claimed in claim 6 wherein the top surface of the top plate in said stack has a plurality of recesses into which said keys may be depressed.

8. Adam encoder for producing output signals representing bits of a character expressed in a second code in response to inputs representing characters of a first code, said encoder comprising: a plurality of OR circuits means responsive to fluid input signals for producing fluid output signals on a plurality of output channels, there being one output channel for each bit of a character expressed in said second code, a manually actuated fluid switch for each character of said first code; fluid conveying means connecting the outputs of said fluid switches to the inputs or said OR circuit means in accordance with said second code; and means for supplying fluid to said switches, each of said switches passing the fluid supplied thereto to its output when actuated, each of said switches comprising a manually depressable key having a keystem for normally blocking said fluid, said keystem having a hole therein for passing said fluid to the output of the switch when said key is depressed.

9. A data encoder for producing output signals representing bits of a character expressed in a second code in response to inputs representing characters of a first code, said encoder comprising: a plurality of OR circuit means responsive to fluid input signals for producing fluid output signals on a plurality of output channels, there being one output channel for each bit of a character expressed in said second code, a manually actuated fluid switch for each character of said first code; fluid conveying means connecting the outputs of said fluid switches to the inputs of said OR circuit means in accordance with said second code; and means for supplying fluid to said switches, each of said switches passing the fluid supplied thereto to its output when actuated, said second code being the excess-three binary code.

Iii. A fluid keyboard comprising: a plurality of stacked plates, each of said plates except the top one having a plurality of channels in its upper face and each of the intermediate plates having a plurality of holes extending therethrough for interconnecting said channels in a predetermined pattern; a plurality of key means each including a keystem having an aperture therein; a second plurality of holes in each of said plates, there being a hole in each plate'for each keystem and corresponding holes in the piates being aligned to receive said keystems; means normally holding said keystems in an undepressed position whereat they block predetermined ones of said channels, each of said apertures being positioned in its keystem such that it aligns with and unblocks a selected one of said predetermined channels when the corresponding References Cited by the Examiner key means is depressed. UNITED STATES PATENTS 11. A fluid keyboard as claimed in claim 10 wherein each holding means comprises a s ring urging its key 2842757 7/1958 Evans 23561 p 2,904,070 9/1959 Lynott 235--201 X means in a first direction and stop means mounted at the 5 3 003 694 10/1961 0 X1 W et a1 235 201 X bottom of each keystem, said stop means being larger 3:129:418 4/1964 De La i l ISL: 235 145 X than said keystem whereby it abuts the bottom of one of said plates, the holes of said second plurality being larger LEO "nary Exammer' than said stop means in plates below said one plate. W. F. BAUER, Assistant Examiner. 

1. A DATA ENCODER FOR PRODUCING OUTPUT SIGNALS REPRESENTING BITS OF A CHARACTER EXPRESSED IN A SECOND CODE IN RESPONSE TO INPUT SIGNALS REPRESENTING CHARACTERS EXPRESSED IN A FIRST CODE, SAID ENCODER COMPRISING: A SOURCE OF FLUID; A PLURALITY OF FLUID OPERATED LOGICAL OR CIRCUITS, ONE FOR EACH BIT OF CHARACTER EXPRESSED IN SAID SECOND CODE, EACH OF SAID OR CIRCUITS HAVING A PLURALITY OF INPUTS AND AN OUTPUT; A PLURALITY OF CHANNEL MEANS CONNECTING SAID SOURCE TO THE INPUTS OF SAID OR CIRCUITS; AND A PLU- 